It is known to incorporate encapsulated perfume compositions in consumer products, such as household care, personal care, and fabric care products. Perfume compositions are encapsulated for a variety of reasons. Microcapsules can isolate and protect perfume ingredients from external suspending media, such as consumer product bases, in which they may be incompatible or unstable. They are also used to assist in the deposition of perfume ingredients onto substrates, such as skin, hair, fabrics or hard household surfaces. They can also act as a means of controlling the spatio-temporal release of perfume.
Aminoplast resin is a common encapsulating medium for perfume compositions. Core-shell microcapsules formed from aminoplast resin are generally quite resistant to leakage when dispersed in aqueous suspending media, even in some surfactant-containing media. Furthermore, when incorporated into consumer products, such as laundry detergents or conditioners, they provide perfumery benefits that are unattainable if perfume is incorporated directly into those products.
Fast moving consumer goods companies have come to rely on encapsulated perfume compositions to add perfumery benefits to their products, and they expect that encapsulated perfumes should not leak excessively during storage, and should provide long-lasting perfume performance when deposited on substrates. However, in addition to these requirements, in order for an encapsulated perfume composition to be perceived favourably by customers, it must be possible for customers to easily carry out all operations related to their use, for example they should be easy for a customer to handle, store, transport, and the like. More particularly, they should be compatible with suspending media, including consumer product bases into which they are to be incorporated.
European patent application EP 2111214 discloses a particular type of aminoplast core-shell microcapsule, in which perfume is encapsulated in shells formed of a melamine-formaldehyde resin cross-linked with resorcinol. These encapsulated compositions are characteristically stable and impart desirable perfumery benefits on consumer products. However, applicant found that the use of resorcinol in the preparation of a slurry of aminoplast microcapsules can lead to an undesirable discoloration of the slurry.
There remains a need, therefore, to provide melamine-formaldehyde microcapsules, which are at least comparable in terms of stability and performance as the prior art resorcinol microcapsules referred to hereinabove, but which are not prone to discoloration.
Applicant surprisingly found that in the preparation of aminoplast microcapsules, replacing resorcinol with a diamine cross-linker, it was possible to form aminoplast microcapsules that were at least comparably stable and performant as prior art aminoplast microcapsules, and furthermore, do not exhibit the discoloration issue.